I changed the valve cover gasket. All seemed to go well then a few days later got the reduced engine power fault. Bad misfire. Hooked up the code reader it suggested the P052B code and several misfires. After a lot of reading, I replaced the CAMshaft sensor (intake and exhaust) and the crankshaft sensor. I also got P0016 and P0012. Engine still running rough after initial start up and service engine light on (reduced power ). Am I missing something? Now I read where the HPFP might be an issue, or I need to replace all the injectors. Any insights. This is a 2011 Z4 E89 3.0L twin Turbo sDrive 35i.